EP 0 840 683 discloses a method of diagnosing an electrically operated brake which includes an electric motor as a drive source for the electrically operated brake. According to this method, a quantity relating to the output of the electric motor is detected upon operation of the electrically operated brake, and the electrically operated brake is determined to be abnormal or defective if the detected quantity does not accurately correspond to the magnitude of a drive signal applied to the electric motor. However, this conventional diagnosing method permits a diagnosis of the electrically operated brake only when the brake is operated during running of the motor vehicle. In other words, the method does not permit a diagnosis of the electrically operated brake before running of the motor vehicle.
In EP 0 924 128, a method is provided for diagnosing an electrically operated brake in an automotive vehicle for abnormality, without or before operation of the electrically operated brake to brake the running vehicle. The electrically operated brake brakes the wheel by applying a friction force, where the friction force is generated by an electric motor of the electrically operated brake. The friction force of the electric motor of the electrically operated brake is applied upon an operation of a brake member. The method includes applying a checking signal to the electric motor of the electrically operated brake while the brake member is placed in a non-braking position. If a signal not normally corresponding to the checking signal is detected, an abnormality of the electrically operated brake is deemed to have been detected.
However, for certain type of vehicles other types of brake systems may often be employed. One example is industrial trucks which normally comprises electromechanical brake systems. In such electromechanical brake systems, an electromechanical brake normally applies a brake force directly onto the drive shaft of an electrical traction motor used to propel and drive the industrial truck. The brake force is applied by the electromechanical brake to the drive shaft using springs, and is released using inductive coils and magnetism. Today, while it is possible to provide a control function in order to check whether or not the electrical circuitry of such electromechanical brakes are operating properly, no solutions are known so far for checking the mechanical integrity and function of electromechanical brakes. Understandably, having properly functioning brakes is an absolute requirement for manually operated vehicles, and is therefore a highly prioritized safety issue.